pvlib.irradiance.gti_dirint(poa_global, aoi, solar_zenith, solar_azimuth, times, surface_tilt, surface_azimuth, pressure=101325.0, use_delta_kt_prime=True, temp_dew=None, albedo=0.25, model='perez', model_perez='allsitescomposite1990', calculate_gt_90=True, max_iterations=30)[source]

Determine GHI, DNI, DHI from POA global using the GTI DIRINT model.

The GTI DIRINT model is described in 1.

Warning

Model performance is poor for AOI greater than approximately 80 degrees and plane of array irradiance greater than approximately 200 W/m^2.

Parameters
• poa_global (array-like) – Plane of array global irradiance in W/m^2.

• aoi (array-like) – Angle of incidence of solar rays with respect to the module surface normal.

• solar_zenith (array-like) – True (not refraction-corrected) solar zenith angles in decimal degrees.

• solar_azimuth (array-like) – Solar azimuth angles in decimal degrees.

• times (DatetimeIndex) – Time indices for the input array-like data.

• surface_tilt (numeric) – Surface tilt angles in decimal degrees. Tilt must be >=0 and <=180. The tilt angle is defined as degrees from horizontal (e.g. surface facing up = 0, surface facing horizon = 90).

• surface_azimuth (numeric) – Surface azimuth angles in decimal degrees. surface_azimuth must be >=0 and <=360. The Azimuth convention is defined as degrees east of north (e.g. North = 0, South=180 East = 90, West = 270).

• pressure (numeric, default 101325.0) – The site pressure in Pascal. Pressure may be measured or an average pressure may be calculated from site altitude.

• use_delta_kt_prime (bool, default True) – If True, indicates that the stability index delta_kt_prime is included in the model. The stability index adjusts the estimated DNI in response to dynamics in the time series of GHI. It is recommended that delta_kt_prime is not used if the time between GHI points is 1.5 hours or greater. If use_delta_kt_prime=True, input data must be Series.

• temp_dew (None, float, or array-like, default None) – Surface dew point temperatures, in degrees C. Values of temp_dew may be numeric or NaN. Any single time period point with a temp_dew=NaN does not have dew point improvements applied. If temp_dew is not provided, then dew point improvements are not applied.

• albedo (numeric, default 0.25) – Surface albedo

• model (String, default 'perez') – Irradiance model. See get_sky_diffuse() for allowed values.

• model_perez (String, default 'allsitescomposite1990') – Used only if model=’perez’. See perez().

• calculate_gt_90 (bool, default True) – Controls if the algorithm evaluates inputs with AOI >= 90 degrees. If False, returns nan for AOI >= 90 degrees. Significant speed ups can be achieved by setting this parameter to False.

• max_iterations (int, default 30) – Maximum number of iterations for the aoi < 90 deg algorithm.

Returns

data (DataFrame) –

Contains the following keys/columns:

• ghi: the modeled global horizontal irradiance in W/m^2.

• dni: the modeled direct normal irradiance in W/m^2.

• dhi: the modeled diffuse horizontal irradiance in W/m^2.

References

1

B. Marion, A model for deriving the direct normal and diffuse horizontal irradiance from the global tilted irradiance, Solar Energy 122, 1037-1046. DOI: 10.1016/j.solener.2015.10.024